React Events
Just like HTML DOM events, React can perform actions based on user events.
React has the same events as HTML: click, change, mouseover etc.
Adding Events
React events are written in camelCase syntax:
onClick
instead of onclick.
React event handlers are written inside curly braces:
onClick={shoot} instead of
onClick="shoot()".
React:
<button onClick={shoot}>Take the Shot!</button>
HTML:
<button onclick="shoot()">Take the Shot!</button>
Example:
Put the shoot function inside the
Football component:
function Football() {
const shoot = () => {
alert("Great Shot!");
}
return (
<button onClick={shoot}>Take the shot!</button>
);
}
const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<Football />);
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Passing Arguments
To pass an argument to an event handler, use an arrow function.
Example:
Send "Goal!" as a parameter to the shoot
function, using arrow
function:
function Football() {
const shoot = (a) => {
alert(a);
}
return (
<button onClick={() => shoot("Goal!")}>Take the shot!</button>
);
}
const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<Football />);
React Event Object
Event handlers have access to the React event that triggered the function.
In our example the event is the "click" event.
Example:
Arrow Function: Sending the event object manually:
function Football() {
const shoot = (a, b) => {
alert(b.type);
/*
'b' represents the React event that triggered the function,
in this case the 'click' event
*/
}
return (
<button onClick={(event) => shoot("Goal!", event)}>Take the shot!</button>
);
}
const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<Football />);
This will come in handy when we look at Form in a later chapter.
